Application of antifoaming agent to reduce defects in a semiconductor electrochemical plating process

ABSTRACT

Embodiments of the invention provide a method and formulations for preventing foam formation inside a plating apparatus prior to or during plating a material on a substrate. In one embodiment, a method for preventing foam formation inside a plating apparatus designed for plating a material on a substrate includes providing an electrolyte solution containing at least one antifoaming agent, at least one metal ion source, and a supporting electrolyte. The method further includes placing the substrate onto a substrate holder of the plating apparatus, immersing the substrate in the electrolyte solution, and depositing the material onto the substrate.

BACKGROUND OF THE INVENTION Field of the Invention

[0001] Metallization of sub-quarter micron sized features is afoundational technology for present and future generations of integratedcircuit manufacturing processes. More particularly, in devices such asultra large scale integration-type devices, i.e., devices havingintegrated circuits with more than a million logic gates, the multilevelinterconnects that lie at the heart of these devices are generallyformed by filling high aspect ratio, i.e., greater than about 4:1,interconnect features with a conductive material, such as copper.Conventionally, deposition techniques such as chemical vapor deposition(CVD) and physical vapor deposition (PVD) have been used to fill theseinterconnect features. However, as the interconnect sizes decrease andaspect ratios increase, void-free interconnect feature fill viaconventional metallization techniques becomes increasingly difficult.Therefore, plating techniques, i.e., electrochemical plating (ECP) andelectroless plating, have emerged as promising processes for void freefilling of sub-quarter micron sized high aspect ratio interconnectfeatures in integrated circuit manufacturing processes.

[0002] In an ECP process, for example, sub-quarter micron sized highaspect ratio features formed into the surface of a substrate (or a layerdeposited thereon) may be efficiently filled with a conductive material,such as copper. ECP plating processes are generally two stage processes,wherein a seed layer is first formed over the surface features of thesubstrate (generally through PVD, CVD, atomic layer deposition (ALD), orother deposition process in a separate tool), and then the surfacefeatures of the substrate are exposed to an electrolyte solution (in theECP tool), while an electrical bias is applied between the seed layerand a copper anode positioned within the electrolyte solution. Theelectrolyte solution is generally rich in copper ions (Cu²⁺) that are tobe plated onto the surface of the substrate, and therefore, theapplication of the electrical bias, i.e., configuring the substrate asthe cathode, causes these ions to be plated onto the seed layer, thusdepositing a layer of the ions on the substrate surface that may fillthe features.

[0003] Conventional electrochemical and electroless plating cellsutilize various types of substrate immersion processes. However,immersion processes are prone to generate bubbles on the substratesurface, which have been shown to cause plating defects, and therefore,minimization of bubble formation is desirable. Further, platingprocesses generally include rotation or agitation of the substrate inthe electrolyte solution, which has been shown to generate a foam at theelectrolyte surface. This foam is also known to cause plating defects,and as such, should be minimized.

[0004] Therefore, a need exists to provide methods and compositions forplating processes that are designed to prevent and/or reduce bubbleand/or foam formation.

SUMMARY OF THE INVENTION

[0005] Embodiments of the invention generally provide a method andformulations for preventing foam formation inside a plating apparatusprior to or during plating a material on a substrate. In one embodiment,a method for preventing foam formation inside a plating apparatusdesigned for plating a material on a substrate includes providing anelectrolyte solution containing antifoaming agent, at least one metalion source, and a supporting electrolyte. The method further includesplacing the substrate onto a substrate holder of the plating apparatus,immersing the substrate in the electrolyte solution, and depositing thematerial onto the substrate.

[0006] Embodiments of the invention may further provide a method forpreventing foam formation inside a plating apparatus, wherein the methodincludes providing an electroless plating solution containingantifoaming agent, immersing the substrate in the electroless platingsolution, and depositing a material layer onto the substrate byelectroless deposition in the electroless plating solution. In oneaspect of the invention, the material layer includes a catalytic seedlayer. In another aspect of the invention, the method further includesdepositing a conductive layer on the substrate over the catalytic seedlayer. In another aspect of the invention, the material layer includes aconductive layer.

[0007] Embodiments of the invention may further provide a method forpreventing foam formation inside an electroless plating apparatusdesigned for electroless plating on a substrate includes providing acatalytic layer solution containing antifoaming agent and immersing thesubstrate in the catalytic layer solution. The method further includesdepositing a catalytic seed layer onto the substrate by electrolessdeposition in the catalytic layer solution and depositing a conductivelayer on the substrate over the catalytic seed layer.

[0008] Embodiments of the invention may further provide a method forpreventing foam formation inside a plating apparatus designed forplating on a substrate having a metal seed layer formed thereon includesproviding an electrolyte solution containing antifoaming agent. Themethod further includes immersing the substrate in the electrolytesolution, and depositing a conductive layer onto the metal seed layer ofthe substrate.

[0009] Embodiments of the invention may further provide a compositionfor a plating bath that is configured to reduce foam formation. Thecomposition may include antifoaming agent selected from the groupconsisting of alcohols, monohydric alcohols, polyhydric alcohols, and C₆to C₂₀ alcohols, such as octal and lauryl alcohols, and combinations andderivatives thereof, at least one metal ion source, and a supportingelectrolyte. Embodiments of the invention further contemplate omittingthe antifoaming agent from the composition and applying the antifoamingagent to the substrate prior to plating. In this embodiment, thesubstrate surface having the pre-wetting antifoaming agent thereonreduces foam when it contacts the bath, and further, may slightlyaccumulate in the bath after several substrates have been processed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] So that the manner in which the features of the invention areattained and can be understood in detail, a more particular descriptionof the invention, briefly summarized above, may be had by reference tothe embodiments thereof, which are illustrated in the appended drawings.It is to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

[0011] FIGS. 1 is a flow diagram illustrating an exemplary platingprocess.

[0012]FIG. 2 is a perspective view of an electroplating system platformuseful to perform electrochemical plating described herein.

[0013]FIG. 3 is a graphical representation of comparison analyses usingthe electrolyte composition of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0014] The words and phrases used herein should be given their ordinaryand customary meaning by one skilled in the art, unless otherwisefurther defined herein.

[0015] Embodiments of the invention include plating methods andelectrolyte compositions configured to reduce, prevent, and/or eliminatebubbles and/or foam formed in a plating apparatus or on a substrate.Methods of the invention can include both the chemical compositionsconfigured to reduce or eliminate bubbles and/or foam, as well as amethod for analyzing electrolyte solutions to determine if foam hasformed or is present on the surface of the solution. The monitoringprocess may include in situ analysis of the plating solution, oralternatively, a sampling of the bath may be cut therefrom and analyzedseparately for the presence of foam.

[0016] Embodiments of the invention also provide a composition forpresenting and/or removing excess bubbles or foams at the surface of thesubstrate without damaging the devices formed on the substrate surface.A typical composition that can be employed to prevent or reduce theexcess bubbles or foam can include antifoaming agent, such compositioncan be used in a plating process together with an electrolyte solutioncontaining at least one metal ion source, a supporting electrolyte, andwater.

[0017]FIG. 1 is a flow chart illustrating an exemplary method 100 of theinvention to prevent and monitor bubble or foam formation in a platingbath. The method 100 of FIG. 1 includes preparing an electrolytesolution at step 110, wherein the solution generally includes anantifoaming agent, a supporting electrolyte, a metal ion source, andwater. The metal ion source may be metal salts generally required forplating a desired material onto a substrate. The metal salts may includeany of the suitable metal salts for the material to be plated on thesubstrate, such as copper salts, noble metal salts, semi-noble metalsalts, Group IV metal salts, etc. Typical materials to be plated thatcan be used herein include, but are not limited to, copper, nickel,gold, silver, and tungsten. The starting electrolyte solution is thusgenerally prepared and pre-mixed before supplying to a platingapparatus.

[0018] The antifoaming agent that can be used herein includes, but isnot limited to, the family of alcohols, such as propanol, butanol,pentanol, hexanol, heptanol, octanol (octyl alcohol), monohydricalcohols, polyhydric alcohols, C6 to C20 alcohols, lauryl alcohol, andany mixtures and derivatives thereof. Other suitable antifoaming agentsthat can be used herein include, but are not limited to, hydrophobicoils, amines, alkyl amines, diamyl methyl amine, amides, acylderivatives of piperazine, alkaline earth, sodium stearate, aluminumstearate, hydrophobic compounds, hydrophobic silica, and combinationsand derivatives thereof. However, generally speaking, the inventorsacknowledge that not all of the above noted compounds and solutions areamenable to plating solutions. Currently, the C6 to C20 alcohols are thepreferred antifoaming agents, however, as technology advances, theinventors acknowledge, and in fact contemplate that the alternativecompounds and solutions that are currently undesirable in a platingsolutions may in fact become practical and preferred.

[0019] In one embodiment, the antifoaming agent may be prepared as astock solution before being added into the electrolyte solution. Forexample, the antifoaming agent can be dissolved in a solvent at aconcentration of between about 1% and about 50%. The solvent can beselected from a variety of compounds that, when prepared in a solution,help to dissolve the antifoaming agent. The compounds suitable as thesolvent for antifoaming agent include, but are not limited to, alcohols(e.g., ethanol, methanol, etc.), siloxanes, polydimethyl siloxane, andcombinations and derivatives thereof.

[0020] The antifoaming agent can be added into the electrolyte solutionto a final concentration of between about 0.002% and about 10% byvolume, such as between about 0.01% and about 5% by volume, depending onthe antifoaming agent and supporting electrolyte used. One workingexample of the antifoaming agent that can be used is at a finalconcentration of about 0.01% of 1-octanol in the electrolyte solutionbecause of its effectiveness and physical stability. Another example isa stock solution of between about 5% and about 30% of 1-octanoldissolved in ethanol that can be added to an electrolyte solution to afinal concentration of between about 0.005% and about 0.25% of 1-octanolin the electrolyte solution, such as about 0.01% or about 0.05% of1-octanol in the electrolyte solution. In general, it is more economicalto dissolve the antifoaming agent into solutions of higher concentration(e.g., a stock solution) to be more effective before diluting into afinal electrolyte solution.

[0021] On the other hand, electroless plating may employ multipleelectrolyte solutions and complex components in an electrolyte. Typicalelectrolyte components for electroless deposition include, but are notlimited to, noble metal salts, semi-noble metal salts, other suitablemetal salts, complexing agents, additives, surfactants, stabilizers, andpH adjusting agents. Examples of noble metals include gold, silver,platinum, palladium, iridium, rhenium, ruthenium, and osmium. Examplesof semi-noble metals include, iron, cobalt, nickel, copper, andtungsten.

[0022] Various supporting electrolytes for electroplating andelectroless plating, as well as plating apparatuses can be purchasedfrom Applied Materials, Inc. of Santa Clara, Shipley Inc. ofMarlborough, Mass., CPI International (CPI) of Santa Rosa, Calif., orEnthone OMI of New Haven, Conn. In one embodiment it is preferred thatthe antifoaming agent used does not interact with the supportingelectrolyte components.

[0023] Returning to the method illustrated in FIG. 1, at step 120 asubstrate is placed onto a substrate holder of a plating apparatusconfigured to use the prepared electrolyte discussed above. Step 120also includes connecting electrical power to a plurality of electricalcontacts positioned in communication with the substrate and immersingthe substrate in the electrolyte solution. A negative voltage is thenapplied to the substrate or the seed layer deposited thereon during theimmersion to prevent etching on the surface of the substrate (e.g., theside walls of vias and trenches) by of the plating electrolyte solution.In general, the antifoaming agent in the electrolyte solution isdesigned to prevent bubble and foam formation on the surface of theelectrolyte solution, which is known to adhere to the plating surfaceand cause defects. The electrolyte solution containing the antifoamingagent results in reduced propensity of the electrolyte solution tocreate and/or sustain bubbles that can be trapped against the surface ofthe substrate. The reduction in the number and size of bubbles reducesthe number of defects typically found on the substrate after plating.

[0024] At step 130, a material is deposited on the substrate by anelectrochemical deposition process, for example, by use of anelectrolyte solution. Agitating the electrolyte solution inside theplating apparatus is generally employed and one of the advantages of theantifoaming agent to be included herein in the electrolyte solution isto prevent bubble or foam formation during such agitation process, by,for example, rotating the wafer.

[0025] At step 140, an optional step is performed to monitor bubble orfoam formation inside the plating apparatus. For example, precisionmonitoring equipment may be used to determine the presence and/orthickness of a foam layer on the surface of a plating bath, as the foamthickness generally has a thickness on the order of a monolayer. Themeasurement may be made in situ, or alternatively, a sample of thesolution may be taken from near the surface of the bath and thenanalyzed in a separate analyzer. The determination that foam is presentcan be used to dispense additional antifoaming agents into the bath, orpossibly to determine when the useful life of the bath has been reachedwhen form forms with the antifoaming agent already contained in thebath. Regardless, at step 150 the substrate may be removed from thecell.

[0026] Electroless plating involves an auto-catalyzed chemicaldeposition process that requires a surface capable of electron transferfor subsequent deposition and nucleation of a conductive material, suchas a catalytic layer containing noble metals, semi-noble metals, andalloys thereof. Noble metals and semi-noble metals are not readilyoxidized, and thus provide a surface capable of electron transfer.However, trapped gas and other bubbles, such as hydrogen gas, are formedin the catalytic layer during an electroless deposition process.

[0027] Therefore, in one embodiment of the invention, a method isprovided for preventing foam formation during electroless deposition ofa catalytic layer. The method generally includes the insertion of thesubstrate into an electroless plating apparatus, dispensing a catalyticlayer solution, removing the catalytic layer solution, then rinsing withwater or other rinsing solutions. For example, the method may includecontacting the substrate with an aqueous catalytic layer solutioncontaining Group IV metal ions, such as tin ions, and then contactingthe substrate with another aqueous catalytic layer solution containingnoble metal ions, semi-noble metal ions, or combinations thereof. Thecatalytic layer solution may generally include antifoaming agent asdescribed herein to prevent foam formation and remove entrapped gas,such as hydrogen gas, formed during electroless deposition. Thus, acatalytic seed layer is deposited onto the substrate by electrolessdeposition in the catalytic layer solution.

[0028] In another embodiment of the invention, a method is provided forpreventing foam formation during electroless deposition of a conductivelayer. The method generally includes the insertion of the substrate intoan electroless plating apparatus, dispensing an electroless platingsolution, then removing the electroless solution, then rinsing thesubstrate with water or other rinsing solutions, and removing thesubstrate from the electroless plating apparatus. In general, anelectroless electrolyte solution containing antifoaming agent and othervarious chemical constituents required for electroless deposition isprepared before placing the substrate onto the substrate holder of theelectroless plating apparatus and having the electroless electrolytesolution supplied on the surface of the substrate. Such electrolessplating solution for a conductive layer may include, but is not limitedto, metal salts for the material of the conductive layer, other suitablesalts, complexing agents, additives, stabilizers, reducing agents, andpH adjusters. For example, an exemplary electroless plating solutionincludes copper sulfate, ethylenediaminetetraacetic acid (EDTA) as acomplexing agent, formaldehyde (HCHO) as the reducing agent, and sodiumhydroxide to adjust the pH of the electroless plating solution. Adiscussion of an exemplary electroless deposition process is describedin the co-pending U.S. patent application Ser. No. 10/059,822, entitled“Electroless Deposition Method Over Sub-Micron Apertures”, filed on Jan.28, 2002, which is incorporated by reference herein.

[0029] A chemical reaction among the principal components of anelectroless deposition process for a conductive layer typicallygenerates gases, such as hydrogen gas. It is believed that the use ofantifoaming agent as described herein helps to remove trapped hydrogengas formed in the conductive layer during the deposition process andthus prevents defect formation on the substrate.

[0030] Plating System:

[0031] Embodiments of the invention provide a plating method andcompositions that can be performed in various plating systems. Oneexample of an electrochemical plating system that may be used herein isan Electra integrated Electro-Chemical Plating (iECP) System availablefrom Applied Materials, Inc., of Santa Clara, Calif. Another example isan ELECTRA CU™ ECP platform, available from Applied Materials, Inc. ofSanta Clara, Calif. The electroplating apparatus is more fully describedin U.S. patent application Ser. No. 09/289,074, entitled“Electro-Chemical Deposition System” filed Apr. 8, 1999, which isincorporated by reference herein. In addition, any system enablingelectrochemical processing using the analytical methods or techniquesdescribed herein may also be used. Another example of a suitable platingapparatus is disclosed in U.S. patent application Ser. No. 10/268,284,entitled, “Electrochemical Processing Cell”, filed on Oct. 9, 2002,which is incorporated by reference herein. A discussion of an exemplaryelectroless deposition system is described in the co-pending U.S. patentapplication Ser. No. 10/059,572, entitled “Electroless DepositionApparatus”, filed on Jan. 24, 2002, is also incorporated by referenceherein.

[0032]FIG. 2 is a perspective view of an electroplating system platform200 of the invention. The electroplating system platform 200 generallyincludes a mainframe 214 having a mainframe substrate transfer robot, aloading station 210 disposed in connection with the mainframe 214, oneor more processing cells 240 disposed in connection with the mainframe,a spin-rinse-dry (SRD) station 212, and an electrolyte replenishingsystem 220 fluidly connected to the one or more electrical processingcells 240. Additionally, the electroplating system platform 200 isenclosed in a clean environment using panels, such as plexiglass panels.

[0033] The mainframe 214 generally includes a mainframe transfer station216 and a plurality of processing stations 218. Each processing station218 includes one or more processing cells 240. An electrolytereplenishing system 220 is positioned adjacent the electroplating systemplatform 200 and connected to the process cells 240 individually tocirculate electrolyte used for the electroplating process. Theelectroplating system platform 200 also includes a control system 222,typically a programmable microprocessor. The control system 222 alsoprovides electrical power to the components of the system and includes acontrol panel 223 that allows an operator to monitor and operate theelectroplating system platform 200.

[0034] The loading station 210 typically includes one or more substratecassette receiving areas 224, one or more loading station transferrobots 228 and at least one substrate orientor 230. The number ofsubstrate cassette receiving areas, loading station transfer robots 228,and substrate orientor 230 included in the loading station 210 can beconfigured according to the desired throughput of the system. Asubstrate cassette containing substrates is loaded onto the substratecassette receiving area 224 to introduce substrates into theelectroplating system platform. The substrate orientor 230 positionseach substrate in a desired orientation to ensure that each substrate isproperly processed. The loading station transfer robot 228 transferssubstrates between the substrate cassette and the substrate orientor230. The loading station transfer robot 228 also transfers substratesbetween the loading station 210 and the SRD station 212.

[0035] The electroplating process cell 240 generally includes a headassembly, a process kit and an electrolyte collector. The head assemblyincludes a substrate holder assembly having a substrate holder 264 and acathode contact ring. The head assembly is provided to position thesubstrate in a processing position and in a substrate loading position.In one embodiment, the head assembly is a rotatable head assembly havinga rotational actuator disposed and attached to the head assembly torotate the head assembly during substrate processing.

[0036] In another embodiment, the electrolyte replenishing system 220includes one or more degasser modules adapted to remove undesirablegases from the electrolyte. The degasser module generally includes amembrane that separates gases from the fluid passing through thedegasser module and a vacuum system for removing the released gases. Thedegasser modules are preferably placed in line on the electrolyte supplyline adjacent to the process cells 240. The degasser modules arepreferably positioned as close as possible to the process cells 240 sothat most of the gases from the electrolyte replenishing system areremoved by the degasser modules before the electrolyte enters theprocess cells. The degasser modules can be placed at many otheralternative positions. A commercially available degasser module isavailable from Millipore Corporation, located in Bedford, Mass.

EXAMPLE

[0037] Examples of reducing, preventing, and/or eliminating foamformation using the electrolyte compositions as described above arepresented herein. Typical concentrations of the electrolyte that may beused are as follows. The concentrations of the inorganic components maybe, for example, between about 5 grams per liter (g/L) to about 80 g/Lof copper sulfate, such as between about 10 g/L and about 60 g/L,between about 30 ppm and about 200 ppm of hydrochloric acid, and betweenabout 5 g/L to about 200 g/L of sulfuric acid. The concentrations of theorganic components in a plating bath that can be analyzed/measured bythe CVS, titration, and other methods known in the semiconductor art,and may be present at concentrations of between about 0.1% to about 2.5%by volume of an accelerator, brightener, or anti-suppressor, betweenabout 0.1% and about 6% by volume of a suppressor, carrier, surfactant,or wetting agent, and between about 0.1% to about 2% by volume of aleveler, over-plate inhibitor, or grain refiner. Various components(both hardware and chemicals) used herein were purchased from Appliedmaterials, Inc. of Santa Clara, Shipley Inc. of Marlborough, Mass., CPIInternational (CPI) of Santa Rosa, Calif., or Enthone OMI of New Haven,Conn.

[0038]FIG. 3 demonstrates the effect of various concentrations of anantifoaming agent on foam formation. Foam thickness is plotted againstvarious concentrations of 1-octanol (dissolved in ethanol first). Twodifferent supporting electrolytes, i.e., a 2 component electrolyte and a3 component electrolyte, with one shown as solid squares and the othershown as solid diamond in FIG. 3, are compared in the absence (zeroconcentration of antifoaming agent) and presence of the addedantifoaming agent. Generally, the foam height drops as the antifoamingagent is added. In FIG. 3, the effective concentration of theantifoaming agent is different for the two supporting electrolytes used.Thus, best antifoaming effect can be achieved at a minimum concentrationof about 0.01% of the antifoaming agent in one supporting electrolyte(solid square) and at a minimum concentration of about 0.016% of thesame antifoaming agent used in another supporting electrolyte (soliddiamond).

[0039] While the foregoing is directed to various embodiments of theinvention, other and further embodiments of the invention may be devisedwithout departing from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

What is claimed is:
 1. A method for preventing foam formation inside aplating cell, comprising: providing an electrolyte solution to the cell,the electrolyte solution containing an antifoaming agent, a metal ionsource, and a supporting electrolyte; placing the substrate onto asubstrate holder of the plating apparatus; immersing the substrate inthe electrolyte solution; and depositing the material onto thesubstrate.
 2. The method of claim 1, further comprising connectingelectrical power to a plurality of electrical contacts disposed tocontact the surface of the substrate after the substrate is placed ontothe substrate holder.
 3. The method of claim 1, further comprisingmonitoring foam formation inside the plating apparatus and dosing theantifoaming agent into the electrolyte solution in accordance with ameasured foam thickness.
 4. The method of claim 1, wherein the metal ionsource is copper.
 5. The method of claim 1, wherein the antifoamingagent is selected from the group consisting of alcohols, monohydricalcohols, polyhydric alcohols, octyl alcohol, C₆ to C₂₀ alcohols, laurylalcohol, and combinations and derivatives thereof.
 6. The method ofclaim 1, wherein the antifoaming agent is dissolved in ethanol.
 7. Themethod of claim 1, wherein the antifoaming agent is 1-octanol dissolvedin ethanol.
 8. The method of claim 1, wherein the antifoaming agent isat a final concentration of between about 0.002% and about 10% by volumein the electrolyte solution.
 9. The method of claim 1, wherein one metalion source comprises a metal salt selected from the group consisting ofcopper salt, noble metal salt, semi-noble metal salt, and combinationsthereof.
 10. The method of claim 1, wherein the supporting electrolytecomprise acid and water.
 11. A method for preventing foam formationinside an electroless plating apparatus, comprising: providing anelectroless plating solution containing at least one antifoaming agent;immersing the substrate in the electroless plating solution; anddepositing a material layer onto the substrate by electroless depositionin the electroless plating solution.
 12. The method of claim 11, whereinthe material layer comprises a catalytic seed layer.
 13. The method ofclaim 12, further comprising depositing a conductive layer on thesubstrate over the catalytic seed layer.
 14. The method of claim 11,wherein the material layer comprises a conductive layer.
 15. The methodof claim 11, wherein the at least one antifoaming agent is selected fromthe group consisting of alcohols, monohydric alcohols, polyhydricalcohols octyl alcohol, C₆ to C₂₀ alcohols, lauryl alcohol, hydrophobicoils, amines, alkyl amines, diamyl methyl amine, amides, acylderivatives of piperazine, alkaline earth, sodium stearate, aluminumstearate, hydrophobic compounds, hydrophobic silica, and combinationsand derivatives thereof.
 16. The method of claim 11, wherein the atleast one antifoaming agent is at a final concentration of between about0.002% and about 10% by volume in the plating electrolyte solution. 17.A method for preventing foam formation inside an electroless platingapparatus designed for electroless plating on a substrate, comprising:providing a catalytic layer solution containing at least one antifoamingagent; immersing the substrate in the catalytic layer solution;depositing a catalytic seed layer onto the substrate by electrolessdeposition in the catalytic layer solution; and depositing a conductivelayer on the substrate over the catalytic seed layer.
 18. The method ofclaim 17, wherein the conductive layer is deposited by a depositiontechnique selected from the group consisting of physical vapordeposition, chemical vapor deposition, electrochemical plating,electroless plating, and combinations thereof.
 19. A method forpreventing foam formation inside a plating apparatus designed forplating on a substrate having a metal seed layer formed thereon,comprising: providing an electrolyte solution containing at least oneantifoaming agent; immersing the substrate in the electrolyte solution;and depositing a conductive layer onto the metal seed layer of thesubstrate.
 20. The method of claim 19, further comprising monitoringfoam formation inside the plating apparatus and dosing the antifoamingagent into the electrolyte solution.
 21. The method of claim 19, whereinthe at least one antifoaming agent is selected from the group consistingof alcohols, monohydric alcohols, polyhydric alcohols octyl alcohol, C₆to C₂₀ alcohols, lauryl alcohol, hydrophobic oils, amines, alkyl amines,diamyl methyl amine, amides, acyl derivatives of piperazine, alkalineearth, sodium stearate, aluminum stearate, hydrophobic compounds,hydrophobic silica, and combinations and derivatives thereof.
 22. Themethod of claim 19, wherein the at least one antifoaming agent isdissolved in at least one solvent selected from the group consisting ofalcohols, ethanol, siloxanes, polydimethyl siloxane, and combinationsand derivatives thereof, before adding to the electrolyte solution. 23.The method of claim 19, wherein the at least one antifoaming agent is ata final concentration of between about 0.002% and about 10% by volume inthe electrolyte solution.
 24. A composition for a plating bath,comprising: at least one antifoaming agent selected from the groupconsisting of alcohols, monohydric alcohols, polyhydric alcohols octylalcohol, C6 to C20 alcohols, lauryl alcohol, and combinations andderivatives thereof; a metal ion source; and a supporting electrolyte.25. The composition of claim 24, wherein the at least one antifoamingagent is first dissolved in at least one solvent selected from the groupconsisting of alcohols, ethanol, siloxanes, polydimethyl siloxane, andcombinations and derivatives thereof.
 26. The composition of claim 24,wherein the at least one antifoaming agent is 1-octanol dissolved inethanol.
 27. The composition of claim 24, wherein the at least oneantifoaming agent is at a final concentration of between about 0.002%and about 10% by volume.
 28. The composition of claim 24, wherein the atleast one metal ion source comprise a metal salt selected from the groupconsisting of copper salt, noble metal salt, semi-noble metal salt, andcombinations thereof.